Coal crushing apparatus are commonly used in longwall coal mining operations to perform a preliminary size reduction on the coal removed from the face of the mine by the longwall shearing machine. The crushed coal thereafter may be removed from the crusher by a suitable conveyer system, such as a "stage loader," although other types of haulage systems (e.g., shuttle cars) may also be used. If a "stage loader" type of conveyer system is used, then the crushed coal is carried away in a continuous manner. If shuttle cars are used, then the coal is carried away in separate loads in a "batch" type process. Coal crushers and stage loaders may also be used in other types of coal mining methods (e.g., shortwall, continuous, etc.), although the longwall mining method is probably the most commonly used method for mining coal today.
Regardless of the particular mining system that is used to extract the coal, control of dust generated during the mining operation is always a critical concern. For example, not only can excessive amounts of airborne dust pose a hazard to mining personnel, high airborne dust levels can pose a significant explosion hazard. One piece of mining equipment that can add to the dust problem is the coal crusher that is used to crush the coal removed from the face by the mining apparatus (e.g., a longwall shearing machine, a continuous miner, etc). Most coal crushers are of the hammer mill type and comprise a rotating drum having a plurality of hammers attached near the periphery of the drum. While the hammers are effective in crushing the coal, they can result the production of significant quantities of dust. While most coal crushers are provided with various types of covers or shields to prevent most of the dust from escaping, some dust almost always escapes, particularly through the coal inlet and outlet ends of the crusher. Another problem is that the rotating drum and hammer assembly tends to act as an air pump, and can induce a significant air flow through the crusher. The air flow induced by the rotating drum and hammers complicates the dust containment problem.
Various types of scrubber systems have been developed in attempts to control the dust generated by the various mining machinery (including coal crushers) that are located at or near the face of the mine. While such scrubber systems are effective in reducing the ambient dust levels, they are not without their problems. For example, most scrubber systems require the provision of electrical power which, while generally available at the mine face, presents yet another complication and cost associated with the mining operation. Such scrubber systems may also contain one or more filters which must be maintained or periodically changed. Many scrubber systems can also generate significant noise levels which add to the noise levels produced by other mining apparatus that may be located nearby.
Consequently, a need exists for a dust control system that is effective at suppressing dust produced by coal crushers that does not suffer the disadvantages of currently available scrubber systems.